This card opens the doors to one of the most powerful sorceries in Magic -- Apex of Power. The spell costs 10 mana, so playing it on its own would be really hard. But with the help of Omnispell Adept you can do it a lot earlier. Here's two possible decks that can make the combo work.
Play lots of card draw spells, such as Chart a Course and Chemister's Insight in order to get Omnispell Adept and Apex of Power. You can also include Brass's Bounty and Fight with Fire or Banefire combo. Last but not least is Omniscience, which would also be a great addition to this type of deck.
Another great opportunity for Omnispell Adept is to use it for casting Nexus of Fate and keep taking turns until you draw Teferi, Hero of Dominaria as your win condition.